1. Field of the Invention
The present invention relates to a filter for rapid extraction of the aromatic substances of a product by a liquid under pressure.
The present invention also relates to an apparatus equipped with a filter of this type.
2. Description of the Prior Art
There was described in French patent Application No. 2 655 529 in the name of the present Applicant an apparatus for the preparation of beverages by rapid extraction of the drinkable aromatic substances of a product which is subjected to a liquid under pressure. In this apparatus, an injector for liquid under pressure opens into a vessel containing the product to be treated, the bottom wall of the treatment vessel being provided with at least one orifice which cooperates with resilient closure means. The orifice is freed by the closure means at least to a partial extent so that, when a predetermined pressure is attained within the treatment vessel, the extract is permitted to flow through a passageway of sufficiently small width to ensure filtration of the liquid which has been in contact with the product to be treated.
When the aforementioned product is ground coffee which is treated with very hot water under pressure in order to obtain "espresso" coffee, there are carried out in a single step the three operations of extraction of aromatic substances, of filtration of the ground coffee in order to allow only the coffee extract to pass through, and of production of froth which is particularly appreciated by users.
However, the particular means described in this prior patent Application are liable to present certain problems of reliability in time.
The object of the present invention is to overcome the disadvantages of the apparatus described in the foregoing and to propose for this apparatus a filter which makes it possible to carry out the three aforementioned operations in a single step, which is easy to construct and the operation of which is particularly reliable over a period of time.